Biomedical subjects

D Vasilyev

Publications and source records attributed to D Vasilyev.

3 recordsLinked to original sources

PubMed2006

A novel method for patch-clamp automation.

An increasing demand of the pharmaceutical industry for automated electrophysiological stations for ion channel drug discovery has recently resulted in the development of several commercial platforms for secondary and safety screening of ion channel modulators. These commercial systems have demonstrated an enhanced throughput, however, often at the expense of some quality-sensitive aspects of traditional patch-clamp recordings. To improve data quality and content, we have developed a patch-clamp robot that fully automates manual patch-clamp recordings, including patch pipette handling, gigaseal formation, obtaining whole-cell or perforated-cell configuration, drug application, and data acquisition. Utilization of glass micropipettes results in high-quality electrophysiological recordings with an overall success rate of about 30% in perforated-cell mode. A fast drug application system with low volume requirements (1-1.5 ml) allows the study of ligand-gated ion channels on a millisecond scale. As proof-of-concept, we present two assays developed for voltage-gated human ether-a-go-go-related and ligand-gated alpha(7) nicotinic receptor ion channels. The system throughput was a single concentration-response curve every 30-40 min or 12-17 6-point concentration-response curves daily, representing a significant improvement of typical manual patch-clamp throughput. This system represents an efficient method for patch-clamp automation without the need for a complex and expensive electrophysiological set-up for cell visualization.

Animals↗

PubMed2005

Aromatase and comparative response to its inhibitors in two types of endometrial cancer.

Aromatase activity (AA) was evaluated totally in 80 tumors collected from primary endometrial cancer (EC) patients. All patients were divided into cases belonging to the types I or II of EC (respectively, 50 and 30 observations). Samples of malignant endometrium from type II demonstrated inclination to the higher AA in comparison with type I samples; the difference reached level of statistical significance in non-smoking patients (p=0.02). Although no positive correlation was revealed between AA in EC tissue and percentage of cells with DNA damage in normal endometrium from the same patients, the rate of DNA damage (percent of comets, comet's tail average length, etc.) was higher in intact endometrium collected from patients with type II of the disease. In 19 tumor samples, CYP19 gene expression was evaluated by RT-PCR and level of mRNA signal demonstrated positive correlation with AA (R(s)=+0.63, p=0.05) in the whole this material. Of note, though, CYP19 mRNA expression was not revealed in six cases, and all of them belonged to the type I of disease. Finally, in 23 EC patients (15 with type I and 8 with type II of the disease) effects of 2 weeks treatment with letrozole (10 pts) and exemestane (13 pts) were evaluated in neoadjuvant setting. Although diminishing of endometrial M-echo signal and the increases in FSH and LH concentration after treatment were more pronounced in type I patients, decrease in tumor PR content (p=0.04) was more revealing in patients with type II of EC; besides, the decreases in AA in tumor tissue by the end of treatment were noted predominantly in patients with lower body weight (BMI <27.5). Thus, although type II of EC is frequently considered as hormone-independent, increased ability of this type of the tumor to estrogen biosynthesis (at CYP19 gene and protein level) may lead to the reconsideration of such conclusion and warrants further investigation. The search of possible ethnic differences in AA and in the biologic response to aromatase inhibitors in EC can be of importance too.

Adult↗

PubMed2002

Switching (overtargeting) of estrogen effects and its potential role in hormonal carcinogenesis.

Peculiarities of the estrogens influence on target tissues is one of the crucial problems in understanding of the estrogen-induced carcinogenesis and anticarcinogenesis mechanisms. Conditions or factors enhancing the genotoxic component in total effect of estrogens (on the uterine tissue, in particular) are very important, since these factors may influence both the hormonal carcinogenesis type and biological properties of the developing hormone-dependent tumors. In this study female rats (3 months of age at the beginning of experiment) have been given plain water (group 1) or 5% ethanol solution over 4 months. Rats which received ethanol were further divided into 6 groups (groups 2-7). During last 2 months of the experiment N-acetylcysteine was given to rats in group 3, ascorbic acid (vitamin C) and alpha-tocopherol (vitamin E)--to group 4, melatonin--to group 5, carnosine--to group 6; the rats in group 7 swam for 5 days a week according to the so called developing schedule. 2.5 weeks before the end of experiment all rats underwent bilateral ovariectomy, and over 11 days preceding the last day of the experiment they received injections of estradiol (2 microg intramuscularly daily). When the experiment was over, estradiol and cholesterol blood levels, progesterone receptors content, peroxidase activity, proliferation index, percent of cells in S and G2/M phases, thickness of endometrium and rate of DNA damage in uterine tissue (COMET assay) and estradiol 2-hydroxylase activity in liver tissue were measured. The conclusion was that administration of 5% ethanol combined with estrogen injections results in genotoxic (G) changes in the uterus, which may be prevented by giving N-acetylcysteine or melatonin. Combination of vitamins C and E enhances some features of hormonal (H) estrogen effects (uterine weight, induction of progesterone receptors), but attenuates the other (proliferation index). Consequently, the combination of N-acetylcysteine and optimal doses of ascorbic acid and alpha-tocopherol may be recommended for prevention of the phenomenon of switching of estrogen effects [PSEE] (e.g. enhancement of G-component and decrease of H-component), observed particularly in cases of the treatment with tobacco smoke or ethanol consumption in more than moderate (15%) concentrations, which lead to the increased risk of genotoxic type of hormonal carcinogenesis.

Animals↗